Two Strains of Streak: A Virus Affecting the Tomato Plant

Abstract

The symptoms produced by a green strain of tomato streak virus 1 upon a variety of Solanaceous plants are described. A yellow variant of the streak virus which appears to have arisen during the culturing of the green strain is also described. This variant produces local yellow spots upon all inoculated leaves of White Burley tobacco.Healthy tobacco plants have been infected with the green strain of the streak virus by spraying them with a virus suspension from an atomiser.The behaviour of the green and yellow virus strains when, co-existing in the tobacco plant is discussed.Filtration through graded collodion membranes shows that the two strains have different filtration end-points and that therefore they can be separated by this means. The difference in filterability is considered to be a quantitative effect and cannot yet be assigned to difference in particle size.Immunity tests have shown that a complete cross-immunity exists between the green and yellow strains of streak themselves, between them and two other strains of streak which produce local lesions and between the green and yellow strains and tobacco virus 1. No immunity was found between the streak viruses and those of tobacco necrosis, tobacco ringspot, tomato spotted wilt and potato virus X.The yellow strain of streak produced local yellow spots on mature leaves of White Burley tobacco. This suggests that the chlorophyll is actually attacked by the virus, and that the formation of the chlorotic spots is not due merely to the inhibition of plastid formation by the virus.